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人至中年,本该看近物眼花,俗称“老花眼”,须配戴合适老花镜方能看书读报,但有些中老年人在戴了一段时间老花镜后,觉得不戴眼镜也不 花了,甚至戴上老花镜反觉得不舒适;还有的人到了该戴老花镜的年龄,眼睛也没有种种不舒适,看东西就是不花。在眼科医生来看,这可能提示眼睛发生了其他疾病: 1.老年性白内障分为皮质型和核型两种,核型占20％,它是由晶体核先开始混浊,又因有水化作用而凸度略增大,屈光指数也增加。两种原因使晶体屈光力增加而产生核性近视,与老花镜(相当远视用的凸透镜)的作用相抵消,所以不用戴花镜了。 2.糖尿病性白内障有糖尿病的老人由于排尿大量增加,血中盐类丢失量相对增多,从而使得眼内血液及房水的渗透
People to middle-aged, should look near dazzled, commonly known as “presbyopia”, to wear appropriate reading glasses before reading newspapers, but some older people wearing a reading glasses for some time, I do not think they wear glasses do not spend And even wear reading glasses anti-feel uncomfortable; there are people who came to the age wearing reading glasses, the eyes are not all kinds of discomfort, to see things is not to spend. In ophthalmologists, this may prompt other diseases occurred in the eye: 1. Senile cataract is divided into two types of cortical and karyotype, Karyotype accounted for 20%, it is the first start by the crystal nucleus turbidity, and because of hydration Effect of a slight increase in convexity, refractive index also increased. There are two reasons to increase the refractive power of the crystal to produce nuclear myopia, and presbyopia (a far-sighted convex lens) offset the role, so do not wear reading glasses. 2. Diabetic cataracts with diabetes due to a large increase in urination, the amount of salt in the blood relative increase, making the eye of blood and aqueous penetration